1. Field of the Invention
The present invention relates to a semiconductor memory device and a method of burn-in testing for performing a test on reliability items for the semiconductor memory device.
2. Description of the Related Art
A burn-in test (hereinafter, BT) is performed for a semiconductor memory device so as to enhance the reliability of the semiconductor memory device.
Recently, as the capacity and the like of semiconductor memory device increases, a rate of test time on reliability items becomes high to overall processing time. Therefore, reduction of BT time is desired.
A conventional semiconductor memory device comprises a plurality of registers, a decision circuit, counters, decoders, a write circuit, a memory cell, and an SA circuit.
By inputting a CLK signal and a first control signal A to a first register, a second control signal B to a second register, a data input signal DIN to a third register, and an address signal to a fourth register and a counter respectively, and outputting a data output signal DOUT of the semiconductor memory device from a fifth register, the BT is performed.
When performing burst operation with making I/O terminals of a semiconductor memory device common, if the semiconductor memory device is controlled with an input signal that is the same as that in ordinary operation, a late write cycle becomes necessary lest a necessary data output signal DOUT and a data input signal DIN should exist simultaneously if write operation is performed after read operation at the time of the ordinary operation. Therefore, this method has a problem that BT time becomes longer.
Conventionally, it is common to perform a BT in only the write operation, in which a differential potential given to a memory cell constructing a semiconductor memory device is high, so as to cast a large stress to the memory cell. Therefore, if only the write operation is continuously performed, the BT time is reduced by omitting the unnecessary late write cycle at the time of performing the BT.